At present, Long Term Evolution (Long Term Evolution) systems work in licensed frequency bands, as bandwidth resources of the licensed frequency bands are lack, thus, frequency bands need to be licensed to use, thereby usage cost of the licensed frequency bands is high. In order to reduce the cost, the LTE systems can be designed to work in unlicensed frequency bands, due to the fact that available bandwidth in the unlicensed frequency bands is large and can be used without license, for example, there is 580 Mhz available bandwidth in 5 Ghz frequency bands.
In actual communication, systems currently working in the unlicensed frequency bands include Wireless Local Area network (WLAN). When the LTE transmits data through the unlicensed frequency bands, and if the LTE systems use a channel of a frequency band, which the WLAN belongs to, in the unlicensed frequency band to transmit data, the WLAN system can also transmit data through the channel, this can result in channel interference. In order to solve a problem of the channel interference, and to realize coexistence of the LTE and the WLAN, a Listen Before Talk (LBT) mechanism is provided currently. The mechanism mainly includes that: the LTE monitors a channel in an unlicensed frequency band; when the channel is monitored to be busy, the unlicensed frequency band is not occupied; or when the channel is monitored to be idle, the channel is occupied. That is, in this situation that the channel is busy, the LTE system can only wait for the channel to be idle, or select another channel to monitor after a timeout. The mechanism for acquiring available channels in the unlicensed frequency bands is blind, a situation that a plurality of channels are continuously monitored to be busy may be occurred, thus, the efficiency of acquiring the available channels in the unlicensed frequency bands is low.